The present invention relates to an electronic musical instrument having musical tone synthesizing function, and more particularly relates to a specific type of the electronic musical instrument constructed to effect synthesis of musical tones according to programable tone control parameters such as timbre data which is inputted and set by a user of the instrument.
As well known, recently there have been developed various types of synthesizers for synthesizing musical tones based on programable tone control parameters set by the user. These types of the synthesizers are constructed such as to generate sophisticated musical tones according to the ton control parameters which are a complex of tone timbre data and tone effect data. The timbre data contains information representative of algorithm of a digital tone generator, characteristic of an envelope generator and so on. The tone synthesis is effected according to these information so as to form a musical tone signal having a specific timbre simulating, for example, piano sound. The effect data contains information used to impart various acoustic effects or variation such as reverberation and delay to the formed musical tone signal.
In such a type of the electronic musical instrument, the above described tone control parameters are divided into upper class data and lower class data in a hierarchical data structure. Namely as shown in FIG. 11, the lower class is comprised of various timbre data stored in a timbre memory VM and various effect data stored in an effect memory EM. On the other hand, the upper class contains performance data comprised of a specific complex of the lower class data, stored in a performance memory PM.
The performance data represents a combination selected from a plurality of timbre data which are set and registered by the user, or represents a combination of timbre data and effect data. The performance data is programed and registered by the user in accordance with a given music performance style. For example, the complex combination indicates a particular setting such that a piano sound and a guitar sound are simultaneously generated during the course of performance, or such that timbre or effect of the generated musical sound is varied in different sections of a keyboard. Namely, the performance memory PM stores various sets of codes of timbre data VM(1)-VM(n) and effect data EM(1)-EM(n) according to the combination information of each performance data.
In practical, as shown in FIG. 12, the hierarchical data structure of the musical tone control parameters are stored such that a sole data memory are divided into three storage areas E1, E2 and E3 which store, respectively, performance data PM(1)-PM(n), timbre data VM(1)-VM(n) and effect data EM(1)-EM(n). The user selects a particular one of the performance data prior to the performance operation so that particular timbre data and effect data designated in the selected performance data are retrieved from the data memory to effect musical tone synthesis responsively.
Normally, the electronic musical instrument having the above noted hierarchical data structure is provided additionally with function to edit o revise the upper and lower class data. This edit function is utilized to revise a content of the previously programed data or to set new data. For example, in order to revise a content of a certain timbre data adopted in a given performance data, this timbre data is edited in the lower class level of the data structure to which the object timbre data belongs. However, in editing of the lower class data within the hierarchical data structure of the timbre data and the performance data associated with each other as shown, for example, in FIG. 13, if the timbre data VM(3) involved in a performance data PM(1) is to be revised or modified by the editing operation, another performance data PM(3) is affected by this editing operation because the latter performance data PM(3) commonly shares the timbre data VM(3) with the former performance data PM(1). The same is true in case that those of the performance data PM(2), PM(4) and PM(35) are affected concurrently by the revision of a commonly shared timbre data VM(6). As described, in the conventional electronic musical instrument, without regard to the associative or hierarchical relation between the upper class data and the lower class data, the lower class data adopted duplicately in a multiple of the upper class data may be uniformly revised, thereby causing the problem that an unintended upper class data might be inadvertently rewritten.